Prior to the advent of the polyurethane roller skate wheel, problems had been encountered in the prior art in the attempts to replace the noisy, expensive and unsatisfactory metal and wooden roller skate wheels with plastic composition wheels. The original plastic composition wheels were often extremely hard and brittle, because an excessive amount of harsh abrasive was used in the composition in order to provide the wheels with an acceptable amount of sliding friction. Accordingly, such prior art wheels had the tendency to chip or crack when subjected to impacts, and they also failed to exhibit the degree of resilience necessary to assure skating comfort and control.
The present-day polyurethane wheel overcomes the defects inherent in the prior art plastic composition wheels in that although hard, they are not brittle, and they exhibit the desired degree of yieldability required in roller skate wheels. However, the polyurethane wheel does not normally exhibit the gripping capabilities of the less desirable prior art wheels. Accordingly, an important object of the present invention is to provide an improved construction for plastic roller skate wheels, for example, of the polyurethane type, which provides a desired high degree of gripping capability thereto without in any way diminishing the favorable characteristics thereof, such as described above, and which contain one or more self contained bearings imbedded concentrically within the plastic rim to permit easy wheel change.